skin pathology Flashcards
describe the layers of skin?
in order:
epidermis
dermis
subcutaneous fat
supportive matrix composed of collagen and elastic fibres
in which layer of skin do you have;
blood vessels, sweat glands, hair follicles, sebaceous glands and nerve fibres
dermis
characterise Palmar-Plantar Skin?
no sebaceous glands
very thick corneal layer - keratin
what is the effect of ageing on skin?
skin becomes fragile and thin with thinner epidermis
The collagen and elastic fibres are also of poor quality
list the Inflammatory Reaction Patterns and their meaning?
• Vesiculobullous - forms bullae
• Spongiotic - becomes oedematous
• Psoriasiform - becomes thickened
• Lichenoid - forms a sheeny plaque
• Vasculitic - associated with vasculitides
Granulomatous - associated with granulomas
characterise bullous pemphigoid?
- They commonly occur in elderly patients on their flexor surfaces
- This condition is characterised by the formation of tense bullae
what is the aetiology of bullous pemphigoid?
an autoimmune disorder driven by IgG and C3, which attack the Basement membrane
DERMO-EPIDERMAL junction
recruit eosinophils which release elastase which further damages the anchoring proteins that are anchoring the lower keratinocytes onto the basement membrane
-> house lifted off foundation (BM)
what is used in the detection of IgG and C3?
found where?
immunofloresence
DERMO-EPIDERMAL junction
In this condition, the blisters are much more flaccid
They rupture easily leaving this raw, red surface underneath ;
this describes which condition?
pemphigus vulgaris
what is the aetiology of pemphigus vulgaris?
- This is an IgG disease
- The damage is occurring within the keratinocyte layers (i.e. within the bricks)
ivx for pemphigus v?
immunofloresence;
IgG lining the layers of KERATINOCYTES
characterise Pemphigus Foliaceus? aetiology?
• You rarely see the intact bullae in this condition because they are so thin that they come off easily
it is the roof that is coming apart (the outer layer of keratinocytes where the stratum corneum is)
This is also IgG mediated
what condition is characterized by round spots of oozing or dry rash, with clear boundaries, often on lower legs.
ITCHY Flexural surfaces
It is usually worse in winter. Cause is unknown, and the condition tends to come and go.
discoid eczema
what are the subtypes of contact dermatitis?
Allergic
- Type 4 delayed hypersensitivity rxn (eeven though allergic reactions are usually type 1) so T cell mediated
Irritant
- touch metal, detergents etc
what are the mediators in the following hypersensitivity reactions;
Type 1
Type 2
Type 3
Type 4
put in order of time taken to respond. give examples
in order
Antibody mediated response;
Type 1 - IgE
Type 2 - IgG or IgM cytotoxic
Type 3 - immune complex mediated
Cell mediated response;
Type 4 - T cell
give examples of the 4 hypersensitivity reactions
Type 1 - anaphylaxis
Type 2 - haemolytic anaemia
Type 3 - SLE, serum sickness
Type 4 - rash
what occurs as a result of scratchin in contact dermatitis?
hyperparakeratosis
what inflammatory reaction type is eczema?
spongiotic because there is fluid/oedema in between the keratinocytes
what inflammatory reaction type is contact dermatitis?
spongiotic
the following are characteristic of what?
Extensor surfaces
White/Silvery plaques
Rapid keratinocyte turnover – skin flakes off quicker than normal!
Psoriasiform pattern
plaque psoriasis
recruitment of neutrophils (forming Munro’s microabscesses) in the epidermis are seen in which condition?
plaque psoriasis
characterise keratinocyte turnover time in p psoriasis vs normal
turnover is around 7 days
vs 50 days in normal people
which conditions exhibit a lichenoid reaction pattern?
lichen planus
the following are characteristic of which condition?
presents as papules and plaques that are slightly purplish in colour on the wrists and arms
In the mouth it presents as white lines (Wickam striae)
lichen planus - t cell mediated
the following is witnessed in which condition?
band-like lymphocytic infiltrate just under the epidermis
lichen planus
mycosis fungiodes
blurred junction between dermis and epodermis due to lymphocyte destruction
the following is witnessed in which condition?
band-like lymphocytic infiltrate just under the epidermis
lichen planus
mycosis fungiodes
blurred junction between dermis and epodermis due to lymphocyte destruction
name a derm condition with a vasculitic inflam pattern?
pyoderma gangrenosum
characterise pyoderma gangrenosum?
• It presents as an ulcer - large and painful
This is often the first manifestation of a systemic disease (e.g. ulcerative colitis, chrons, leukaemia)
define a granuloma?
Granuloma – collection of activated histiocytes (macrophages)
characterise Seborrhoeic Keratosis?
entrapped keratin surrounded by a proliferating (orderly) epidermis
common in the elderly
microscope you will see horn cysts
Pigmented cauliflower
the following is witnessed in which condition?
smooth surface
They are non-mobile and tend to have a punctum
squamous epithelium along the lining
• They can be very smelly
Sebaceous/Epidermal Cyst
Rodent Ulcer is aka?
basal cell carcinoma
the following is witnessed in which condition?
rolled, pearly edge with a central ulcer and telangiectasia
• It doesn’t tend to cause any significant morbidity or mortality
• However, they can be disfiguring if they form on the face
basal cell carcinoma
aetiology of basal cell carcinoma?
arises from the keratinocytes along the bottom of the epidermis
• These cells then infiltrate through the basement membrane
• They can spread via the nerves and lymphovascular system or they can cause local infiltration
BCCs are locally infiltrative but they don’t metastasise
Bowen’s Disease is what type of cancer?
squamous cell carcinoma in situ
precancerous lesion
Lots of keratin seen
the following is witnessed in which condition?
Melanocytes expand from the basal layer and form nests
junctional naevus
define pagetoid spread?
melanocytes are starting to migrate upwards through the epidermis - this is NOT normal
upon reaching dermis, become mitotically active and lack the ability to mature -> malignant melanoma
melanoma with a thickness > 4 mm, has ______ mortality ?
a very high (> 50%)
how is melanoma staged?
Breslow thickness used for malignant melanoma
DIAMETER does NOT matter in melanoma its about thickness
what are the stages of the Hair follicle cycle?
the hair follicles cycle continuously from anagen to telogen returning to anagen through growth of the lower segment.
anagen -> catagen -> telogen and repeat
